Regional anesthesia and pain medicine
-
Reg Anesth Pain Med · Nov 2007
Local anesthetics have different mechanisms and sites of action at recombinant 5-HT3 receptors.
In addition to their blockade of voltage-dependent sodium channels, the action of local anesthetics at 5-hydroxytryptamine-3 (5-HT3) receptors may be clinically relevant. Because local anesthetics have different clinical properties, we have tested the hypothesis that differences in interactions at the 5-HT3 receptor may be clinically relevant by investigating the effects of 4 local anesthetics on recombinant wild-type and 4 mutant 5-HT3A receptors. ⋯ The ester type local anesthetics, procaine and tetracaine, may act at a different site on the 5-HT(3A) receptor and with a different mechanism than the amide-type local anesthetics. Clinical differences between local anesthetics may be at least partially due to differences in interactions at the 5-HT3A receptor.
-
In neuraxial anesthesia, increase of skin temperature is an early sign of successful block. Yet, during peripheral nerve block of the lower extremity, increase in skin temperature is a highly sensitive, but late sign of a successful block. We hypothesized that after interscalene brachial plexus block, a rise in skin temperature follows impairment of sensation during successful nerve block and occurs only distally, as observed in the lower extremity. ⋯ Assessment of skin temperature cannot predict the success of an interscalene brachial plexus block of the axillary and musculocutaneous nerve. Distally, the increase of skin temperature has a high sensitivity and specificity but occurs later than the loss of sensory and motor functions. Therefore, the measurement of skin temperature during interscalene blockade is of limited clinical value.